Urushiols are a group of alkylcatechols produced by plants which cause mild to severe allergenic responses. These substances are produced by plants, including but not limited to the genus Rhus, which includes poison ivy, poison oak and poison sumac. Exposure to the plant causes oily urushiols to be transferred to the skin. The result is painful contact dermatitis followed, at times, by infection. The viscous oils are water-insoluble and are washed off only with difficulty. The attempt to clean the skin of the urushiols often results in further spreading of the urushiols resulting in increased irritation and discomfort. In some instances, burning of the plants causes the urushiols to be discharged into the air and carried on the wind. In such instances, not only the skin and mucous membranes, but also the lungs may be affected by exposure to the urushiols.
Protective clothing has often been worn as a means of prevention. Treatment has usually consisted of application of steroid preparations and of soothing lotions such as Calamine lotion. None of these treatments have provided particularly satisfactory results.
Attempts to desensitize susceptible persons by administration of urushiols by mouth have proven disappointing. Part of the problem is that the allergenic urushiol liquid dosage forms are inherently hard to handle. The frequent side reactions have resulted in considerable discomfort to the patients.
The patent literature discloses several compositions for using in treating irritation resulting from exposure to urushiols. U.S. Pat. No. 3,749,772 discloses a method of blocking the urushiols by application of a film-forming polymer and a cross-linking agent. No method of complexing the urushiols for removal from the skin is disclosed therein. U.S. Pat. No. 4,199,575 discloses a composition containing non-aqueous alkyl/aryl polyglycol ether to treat dermatitis resulting from exposure to plants of the Anacardiacea family. U.S. Pat. No. 4,451,453 discloses a method of treating skin exposed to urushiols by application of acrylic copolymer to adsorb the irritating agent. U.S. Pat. Nos. 4,861,584 and 5,017,361 disclose a method of protecting the skin from contact with allergen by application of a barrier composition containing smectite clay and quaternary ammonium compounds to absorb and block the urushiols.
From the general literature, it is suggested that compositions containing bentonite, kaolin, and silicone could be used to protect against exposure to poison ivy and poison oak dermatitis. (Arch Dermatol, 125, April 1989, 499-501).
The prior art inventions pose several problems. First of all, it is not effective to treat skin already exposed to urushiols with a blocking agent. The blocking agents are, furthermore, often uncomfortable and inconvenient to use.
Cyclodextrins are cyclic oligomers of glucose that are derived from starch, and that consist of rings of glucose molecules. The three most common forms, alpha-, beta-, and gamma-cyclodextrins consist, respectively, of six, seven and eight glucose molecules. The molecules contain cavities that have lipophilic properties. Cyclodextrins have been used as delivery agents for water-insoluble drugs for topical, oral and parenteral delivery. They have also been used to deliver cosmetic preparations to the skin. Cyclodextrins present an advantage as natural substances that are nontoxic and nonirritating to the skin.
U.S. Pat. No. 4,352,794 discloses and claims a method of treating acne using beta-cyclodextrin. No suggestion is made therein that the cyclodextrins have use for protection or treatment of patients that have been exposed to urushiols or that the compositions should be applied on a solid support or in form of a spray.